Showing papers on "Thunderstorm published in 1984"
TL;DR: In this article, the impact of the regime-to-regime variations on empirical rain estimation schemes based on satellite-observed cloud height or cloud temperature information is discussed and a rain estimation approach based on model-generated cloud-rain relations is outlined.
Abstract: Observational studies of thunderstorm cloud height-rainfall rate and cloud height-volume rainfall rate relations are reviewed with significant variations being noted among climatological regimes. Analysis of the Florida (summer) and Oklahoma (spring) relations are made using a one-dimensional cloud model to ascertain the important factors in determining the individual cloud-rain relations and the differences between the two regimes. In general, the observed relations are well simulated by the model-based calculations. The generally lower predicted rain rates in Oklahoma (as compared to Florida) result from lower precipitation efficiencies which are due to a combination of larger entrainment (related to larger vertical wind shear) and drier environment. The generally steeper slope of the Oklahoma rain rate height curves is shown to be due to a stronger variation in maximum vertical velocity with cloud top height, which, in turn, is related to the greater static stability in the range of cloud tops. The impact of the regime-to-regime variations on empirical rain estimation schemes based on satellite-observed cloud height or cloud temperature information is discussed and a rain estimation approach based on model-generated cloud-rain relations is outlined.
89 citations
TL;DR: In this paper, a methodology for obtaining pressure perturbations and buoyancy in thunderstorms observed with Doppler radar is described and applied to two tornadic thunderstorms. Extracted thermodynamic information is combined with kinematic analyses to study observed severe storm processes.
Abstract: A methodology for obtaining pressure perturbations and buoyancy in thunderstorms observed with Doppler radar is described and applied to two tornadic thunderstorms. Extracted thermodynamic information is combined with kinematic analyses to study observed severe storm processes. The intensification of tornado parental circulations (mesocyclones) during tornadogenesis is found to be associated with deepening pressure deficits in lower storm levels. Upward directed perturbation pressure forces in the vicinity of the mesocyclone are reduced and can be reversed as the low-level vorticity amplifies. The sudden formation of concentrated rear downdrafts, commonly observed in tornadic thunderstorms, apparently stems from the vertical pressure gradient reversal. Reduced upward pressure forces decrease the storm's ability to lift low-level negatively buoyant air at the base of the updraft. Further, the restructured pressure forces create a flux of air parcels into the mesocyclone from higher levels on the s...
61 citations
TL;DR: In this article, a severe thunderstorm spawned two tornadoes which moved across a portion of metropolitan Denver, causing damage totaling over $1 5 million, and the tornadoes were classified as strong F2 intensity.
Abstract: On the afternoon of 3 June 1981 a severe thunderstorm spawned two tornadoes which moved across a portion of metropolitan Denver. The tornadoes were classified as strong F2 intensity, and caused damage totaling over $1 5 million. The synoptic-scale setting for this event was similar to that associated with many other occurrences of severe convection in eastern Colorado, with post-frontal moist southeasterly upslope flow at low levels and southwesterly flow aloft in advance of an approaching trough. We chose to study this event in part because of its occurrence within the PROFS (Program for Regional Observing and Forecasting Services) surface mesonetwork. Emphasis is placed on mesoscale evolution culminating in the formation of the tornadic storm. A zone of surface convergence and cyclonic vorticity developed during the early daylight hours over and north of Denver between southeasterly flow over the plains and a region of lighter, generally northerly flow just east of the foothills. The tornadic s...
59 citations
TL;DR: In this paper, an analysis of radar echoes from lightning at the moments of strikes to the NASA Langley Research Center's F-106B instrumented airplane proves that the airplane itself triggers the lightning, rather than intercepting naturally occurring flashes.
Abstract: The analysis of radar echoes from lightning at the moments of strikes to the NASA Langley Research Center's F-106B instrumented airplane proves that the airplane itself triggers the lightning, rather than intercepting naturally occurring flashes. In 1982 the UHF band radar at the NASA Goddard Space Flight Center/Wallops Flight Facility was used to guide the F 106B through the upper regions of thunderstorms so that the airplane might be struck by lightning. The UHF band radar data was analyzed to determine the nature and characteristics of direct lightning strikes to the airplane, and the airborne data was used to document the environmental con ditions favorable for such strikes The echo characteristics of the strikes were similar to those of intracloud flashes, and indicated that most of the time the airplane was part of the lighting channel. The probability of a direct strike to the F-106B during storm penetrations (PDS) is defined here as the ratio of the number of direct strikes to the airplane to the total number of flashes occurring in the radar resolution volume containing the airplane Correlations between the PDS and the intensity of rain, the intensity of turbulence, the ambient temperature, and the lightning flash rate in the storms penetrated were obtained The correlations indicated that the highest risk for the F-106B to be struck by lightning during penetrations in the upper regions of thun derstorms occurred under the following conditions: 1) ambient temperatures of -40 C and colder; 2) negligible to light precipitation; 3) negligible to light turbulence; and 4) lightning flash rates of < 10 per minute
43 citations
TL;DR: In this paper, an analysis of the network and other data presented by the U.S. National Severe Storms Laboratory showed that the associated disturbance was an internal undular bore propagating on a low-level stable layer, similar to "morning glory"-type disturbances, which are common at certain times of the year in parts of northern Australia.
Abstract: Early in the morning on 9 June 1982 a system of traveling wave cloud lines passed over 0klahoma, and in particular, over the relatively dense mesonetwork of surface stations, including the instrumented 444 m KTVY television tower, operated by the U.S. National Severe Storms Laboratory. An analysis of the network and other data presented herein shows that, in structure, the associated disturbance was an internal undular bore propagating on a low-level stable layer, similar to “morning glory”-type disturbances, which are common at certain times of the year in parts of northern Australia. Moreover, the speed of propagation of the component bore-waves is in broad agreement with theoretical calculations. There is evidence that the disturbance emanated late the previous evening from an area of rapidly growing intense thunderstorms located more than 400 km north-northwest of the surface mesonetwork. Possible mechanisms for generation are discussed, but the data pertaining to genesis are insufficient to ...
42 citations
TL;DR: A commercial lightning-locating system (LLS) was employed in the study of lightning phenomenology in the Tampa Bay area of Florida as mentioned in this paper, where the LLS output included the time, location, number of strokes per flash, and initial peak magnetic field value of first strokes for lightning ground flashes lowering negative charge.
Abstract: A commercial lightning-locating system (LLS) was employed in the study of lightning phenomenology in the Tampa Bay area of Florida. The LLS output included the time, location, number of strokes per flash, and initial peak magnetic field value of first strokes for lightning ground flashes lowering negative charge. Attention is given to the design and the operation of the LLS, and the experimental results. Measured properties of each of 111 storms are given in a number of tables. It was observed that the apparent motion associated with the lightning activity in storm systems was not due to the motion of the individual single-peak and multiple-peak storms but rather to the successive growth of new storms near previously active storms.
42 citations
01 Jan 1984
TL;DR: In this article, the authors deal with electric fields and currents generated in thunderstorms and discuss the characteristics of the global electric circuit, including the area of charge separation, lightning events as breakdown electric currents, and sferics as the electromagnetic radiation of the lightning currents.
Abstract: In the following five chapters, we deal with electric fields and currents generated in thunderstorms Thunderstorms behave like batteries which are connected with the highly conducting ionosphere and earth via the barely conducting lower and middle atmosphere (Fig 31) The passive electric quasicontinuous current flowing outside the thunderstorm regions down to the earth is part of the global electric circuit In this chapter, we outline some characteristics of the global electric circuit In the following chapters, we discuss the thunderstorm as area of charge separation, lightning events as breakdown electric currents, and sferics as the electromagnetic radiation of the lightning currents
42 citations
TL;DR: In this article, a conceptual model of a small mesoscale convective system was developed for the south-west of England, which was observed to have many of the features previously found in the United States.
Abstract: Frequent digital cloud imagery from Meteosat and precipitation patterns from radar have been analysed together with surface observations and conventional and satellite soundings, to develop a conceptual model of a small mesoscale convective system. The system, observed to the south-west of England, had many of the features previously found in the United States, where the term mesoscale convective system or complex is applied to a cluster of thunderstorms that generates a common cirrus shield of mesoscale dimensions. A mesoscale region of fairly uniform, essentially stratiform, rain developed beneath the cirrus shield downwind of the active convection. Thunder was widespread throughout the precipitation area which was also characterized by a surface mesohigh. The mesoscale convective system, and another similar one before it, lasted for about half a day each, during which time they produced large falls of rain over an extensive area. The mesoscale convective systems developed in a region of locally strong baroclinicity on the eastern flank of a cut-off low. They happened to form over the sea and were decoupled from the surface by a cool easterly boundary layer flow. Their development could be traced to the onset of advection from France of warm moist air with a wet-bulb potential temperature in excess of 18 °C at 850 mb. The arrival of this air coincided with the intensification of the SE-ly flow around the approaching cut-off low.
42 citations
TL;DR: In this article, the authors investigated the nature and apparent origin of a mesoscale clear zone and associated frontal line convection (a line of cumulus congestus clouds along an intensifying cold front) which appeared just prior to the explosive development of a line of severe thunderstorms at the cold front.
Abstract: The present investigation is concerned with the nature and apparent origin of a mesoscale clear zone and associated frontal line convection (a line of cumulus congestus clouds along an intensifying cold front) which appeared just prior to the explosive development of a line of severe thunderstorms at the cold front. It is pointed out that the clear zone formed immediately behind the cold front in southeastern Kansas and northeastern Oklahoma during the afternoon of April 16, 1982. Sequential displays of GOES-East satellite imagery are considered. The mechanism which seems to explain best the observations is a thermally direct frontogenetic circulation resulting from the combined effects of the synoptic-scale wind deformation field and mesoscale differential sensible heating.
40 citations
TL;DR: In this paper, the average diurnal variation of lightning in a Florida seacoast environment was determined using data derived from a large network of electric field mills, and the results showed that the actual lightning tends to stop one to two hours before the recorded thunder, consistent with previous determinations of the times of maximum rainfall and maximum rainfall rate.
Abstract: Data derived from a large network of electric field mills are used to determine the average diurnal variation of lightning in a Florida seacoast environment. The variation at the NASA Kennedy Space Center and the Cape Canaveral Air Force Station area is compared with standard weather observations of thunder, and the variation of all discharges in this area is compared with the statistics of cloud-to-ground flashes over most of the South Florida peninsula and offshore waters. The results show average diurnal variations that are consistent with statistics of thunder start times and the times of maximum thunder frequency, but that the actual lightning tends to stop one to two hours before the recorded thunder. The variation is also consistent with previous determinations of the times of maximum rainfall and maximum rainfall rate.
37 citations
TL;DR: The Platteville VHF Doppler radar continuously measured the vertical wind velocity during a 12-day period in late July and early August 1981 with range gates centered at 33, 57, 81, 105, 129, 153, 177, and 201 km above sea level as mentioned in this paper.
Abstract: The Platteville VHF Doppler radar, located on the Colorado piedmont near Platteville, Colorado, continuously measured the vertical wind velocity during a 12-day period in late July and early August 1981 Measurements were made every 25 min on the average with range gates centered at 33, 57, 81, 105, 129, 153, 177, and 201 km above sea level Periods of active thunderstorms were identified from the PPI maps from the National Weather Service 10 cm weather radar at Limon, Colorado When no thunderstorm activity was present, the vertical velocity fluctuations were small and erratic But a few hours after strong thunderstorm activity began, large quasi-sinusoidal wave trains with periods of about 40 min were observed Power spectra of the vertical velocity time series showed enhancements at all frequencies during thunderstorm activity, but for periods longer than 30 min the enhancements were larger, particularly for the mid-tropospheric range gates from 57 to 129 km Some of the implication
TL;DR: In this paper, a space-time mapping of VHF sources from four severe storms on June 19, 1980 reveals that lightning processes for cloud-to-ground (CG) and large intracloud (IC) flashes are confined to an altitude below about 10 km and closely associated with the central regions of high reflectivity.
Abstract: Space-time mapping of VHF sources from four severe storms on June 19, 1980 reveals that lightning processes for cloud-to-ground (CG) and large intracloud (IC) flashes are confined to an altitude below about 10 km and closely associated with the central regions of high reflectivity. Another class of IC flashes produces a splattering of sources within the storms' main electrically active volumes and also within the large divergent wind canopy aloft. There is no apparent temporal association between the small high altitude IC flashes that occur almost continuously and the large IC and CG flashes that occur sporadically in the lower portions of storms.
TL;DR: In this paper, the authors describe the changes to equipment and data sources and present overall results for the 1979 thunderstorm season, where appropriate, these are linked to 1978 data and to data obtained from equipment which operated on a year-long basis.
Abstract: Experience in the Tampa Bay area during August 1978 thunderstorms resulted in significant improvements in the field work carried out during 1979. This paper describes the changes to equipment and data sources (see [1, 2]), and presents overall results for the 1979 thunderstorm season. Where appropriate, these are linked to 1978 data and to data obtained from equipment which operated on a year-long basis.
TL;DR: The formation of the lower positive charge center in thunderstorms and the initiation of a lightning flash which precedes the commonly observed gush of rain on the ground may be explained in terms of this charging process as discussed by the authors.
Abstract: Laboratory studies of charge transfer, when vapor-grown ice crystals bounce off a hailstone in simulated thunderstorm conditions, have shown that the sign and magnitude of the charge separated is a sensitive function of the cloud and cloud particle properties. In general, at temperatures colder than −20°C, hail becomes negatively charged, but at warmer temperatures it becomes positively charged. The formation of the lower positive charge center in thunderstorms and the initiation of a lightning flash which precedes the commonly observed gush of rain on the ground may be explained in terms of this charging process.
01 May 1984
TL;DR: In this article, an improved lightning ground strike climatology has been obtained from thunderstorm duration data recorded by 450 air weather stations by using the equation N/sub s/ = 0.054H/sup 1/ /sup 1/, where H is the number of strikes per square kilometer and S is the storm duration in hours.
Abstract: An improved lightning ground strike climatology has been obtained from thunderstorm duration data recorded by 450 air weather stations. From lightning strike location data collected in Florida and Oklahoma, it was found that strike density could be estimated from thunderstorm duration by the equation N/sub s/ = 0.054H/sup 1/ /sup 1/, where N/sub s/ is the number of strikes per square kilometer and H is thunderstorm duration in hours. This relationship was applied to thunderstorm duration data from the aviation stations to obtain lightning strike density for the contiguous United States.
TL;DR: In this paper, infrared and visible imagery from VAS are used to delineate mid and lower-tropospheric moisture fields for a variety of severe storm cases in the southern and central United States.
Abstract: Infrared and visible imagery from VAS are used to delineate mid- and lower-tropospheric moisture fields for a variety of severe storm cases in the southern and central United States. The ability of sequences of images to isolate areas of large negative vertical moisture gradients and apparent convective instability prior to the onset of convective storms is assessed. A variety of image combination procedures are used to deduce the stability fields which are then compared with the available radiosonde data. The results for several severe storm cases indicate that VAS can detect mid- and low-level mesoscale water vapor fields as distinct radiometric signals. The VAS imagery shows a strong tendency for thunderstorms to develop along the edges of bands of midlevel dryness as they overtake either preexisting or developing low-level moisture maxima. Image sequences depict the speed with which deep moist and dry layers can develop and move.
01 Sep 1984
TL;DR: In this paper, it was shown that substances produced by thunderstorm electrical discharges can be introduced directly into the stratosphere, and the cause and nature of the discharges above the cloud are not clear.
Abstract: Nocturnal thunderstorms were observed from above and features of cloud structure and lightning which are not generally visible from the ground are discussed. Most, lightning activity seems to be associated with clouds with strong convective cauliflower tops. In both of the storms lightning channels were visible in the clear air above the cloud. It is shown that substances produced by thunderstorm electrical discharges can be introduced directly into the stratosphere. The cause and nature of the discharges above the cloud are not clear. They may be produced by accumulations of space charge in the clear air above the cloud. The discharges may arise solely because of the intense electric fields produced by charges within the cloud. In the latter case the ions introduced by these discharges will increase the electrical conductivity of the air above the cloud and increase the conduction current that flows from the cloud to the electrosphere. More quantitative data at higher resolution may show significant spectral differences between cloud to ground and intracloud strokes. It is shown that electric field change data taken with an electric field change meter mounted in an airplane provide data on lightning discharges from above that are quite similar to those obtained from the ground in the past. The optical signals from dart leaders, from return strokes, and from continuing currents are recognizable, can be used to provide information on the fine structure of lightning, and can be used to distinguish between cloud to ground and intracloud flashes.
TL;DR: In this paper, the average annual frequencies of thunderstorm days across New York State for the period 1978-81 were estimated using archived radar reports, derived from the National Weather Service radar network, using an experimentally derived relationship between radar reflectivities and the presence and intensities of thunderstorms.
Abstract: Archived radar reports, derived from the National Weather Service radar network, were used to estimate the average annual frequencies of thunderstorm days across New York State for the period 1978–81. The archival records consist of manually-digitized radar (MDR) data, available on magnetic tapes and arranged as hourly, digitally-encoded radar reflectivity values within a high-resolution grid of reporting blocks, each 45 × 45 km. Analyses of these data made use of an experimentally-derived relationship between radar reflectivities and the presence and intensities of thunderstorms. The radar-based thunderstorm day climatology generally agreed to within 15% of conventional, surface-based thunderstorm day statistics reported for the same period by National Weather Service (NWS) offices located within range of two or more network radars in the State. Poorest agreement between annual totals was found at selected NWS offices in the Greater New York City Metropolitan Area and northward into the lower Hu...
TL;DR: The UHF and S-band radar at NASA/Wallops Island Research Facility in Virginia, U.S.A. have been used to relate lightning activity with altitude and with the reflectivity structure of thunderstorms as discussed by the authors.
Abstract: The UHF-(70.5 cm wavelength) and S-band (10 cm wavelength) radar at NASA/Wallops Island Research Facility in Virginia, U.S.A. have been used to relate lightning activity with altitude and with the reflectivity structure of thunderstorms. Two centers of lightning flash density were found; one between 6 and 8 km altitude and another between 11 and 15 km. Previously announced in STAR as N83-31206
TL;DR: In this paper, results from an initial set of comparative experiments in a project which utilizes a three-dimensional convective storm model are presented, which are related to four comparative experiments, designated Cases A through D. One of two scientific questions considered involves the dynamical processes, either near the cloud top or well within the cloud interior, which contribute to organize cloud thermal patterns such as those revealed by IR satellite imagery for some storms having strong internal cloudscale rotation.
Abstract: The present investigation is concerned with results from an initial set of comparative experiments in a project which utilize a three-dimensional convective storm model. The modeling results presented are related to four comparative experiments, designated Cases A through D. One of two scientific questions considered involves the dynamical processes, either near the cloud top or well within the cloud interior, which contribute to organize cloud thermal patterns such as those revealed by IR satellite imagery for some storms having strong internal cloud-scale rotation. The second question is concerned with differences, in cloud-top height and temperature field characteristics, between thunderstorms with and without significant internal cloud-scale rotation. The four experiments A-D are compared with regard to both interior and cloud-top configurations in the context of the second question. A particular strong-shear experiment, Case B, is analyzed to address question one.
01 Jan 1984
TL;DR: In this article, direct lightning strike data and associated flight conditions were collected from 1980 to 1983 during 742 thunderstorm penetrations with a NASA F-106B in Oklahoma and Virginia.
Abstract: The direct lightning strike data and associated flight conditions recorded from 1980 to 1983 during 742 thunderstorm penetrations with a NASA F-106B in Oklahoma and Virginia are studied with an emphasis on aircraft protection design. The individual lightning attachment spots were plotted on isometric projections of the aircraft to identify lightning entry and exit points and swept flash patterns. The altitudes, ambient temperatures, turbulence, and precipitation at which the strikes occurred are summarized and discussed. It was noted that peak strike rates (0.81 strikes/min and 3 strikes/penetration) occurred at altitudes between 11 km and 11.6 km corresponding to ambient temperatures between -40 C and -45 C. The data confirmed that initial entry and exit points most frequently occur at aircraft extremities, in this case the nose boom, the wing tips, the vertical fin cap, and the afterburner. The swept-flash attachment paths and burn marks found in this program indicate that the mid-span areas of swept aircraft may be more susceptible to lightning than previously thought. It was also found that lightning strikes may attach to spots within the engine tail pipe.
TL;DR: The characteristics and environment of low-precipitation severe thunderstorms in the Southern Plains have been summarized by Bluestein and Parks in 1983 as discussed by the authors, and photographic documentation is given here of several storms not previously shown.
Abstract: The characteristics and environment of low-precipitation severe thunderstorms in the Southern Plains have been summarized by Bluestein and Parks in 1983. Photographic documentation is given here of several storms not previously shown.
01 Sep 1984
TL;DR: In this article, the infrared properties and structures of some anvils emanating from local thunderstorms were studied by lidar and infrared radiometry at Darwin, tropical Northern Australia, where the average altitude and calculated wide-band greybody flux emittance were 11 km and 0.65 respectively.
Abstract: The infrared properties and structures of some anvils emanating from local thunderstorms were studied by lidar and infrared radiometry at Darwin, tropical Northern Australia. The anvils were typically from 1 to 2 km deep, at altitudes from 7 to 16 km and at temperatures from −15 to −70°C. There was a rough dependence of infrared emittance on temperature, but there was also a dependence on the age of the anvil. The average altitude and calculated wide-band greybody flux emittance were 11 km and 0.65 respectively. One dense cloud appeared “superblack” when observed from below, due to reflection of upwelling warm radiation from the surface. The magnitude of the effect agreed within experimental error with that predicted from computations on a model cloud of ice cylinders, but was about twice that computed for a model of ice spheres. Calculated rates of heating in the very cold clouds were very high, reaching 4°C h−1 near cloud base. The survival of these clouds for several hours suggests that the ab...
TL;DR: In this article, an orthogonal principal component analysis of National Climatic Center summer thunderstorm frequency data over Virginia revealed five statistically significant modes of variation, including power spread statewide, while in others it was concentrated over a few small regions.
Abstract: An orthogonal principal component analysis of National Climatic Center summer thunderstorm frequency data over Virginia revealed five statistically significant modes of variation. In some, power was spread statewide, while in others it was concentrated over a few small regions. A similar analysis was performed on the NCAR record of monthly 500 mb heights over North America, and four significant height patterns were determined. Multiple regression was used to relate the individual thunderstorm components to the upper-air patterns. The fit of each time series of the first four thunderstorm components by the 500 mb patterns was statistically significant, with approximately one-third of the variance of the thunderstorm pattern explained. A subsequent canonical correlation revealed one significant multivariate relationship. The results provide statistically significant evidence for the linkage between macroscale flow patterns and mesoscale convective storms.
01 Jul 1984
TL;DR: In this article, a theoretical model is presented and described that unifies the complex influence of several factors on spatial and temporal variation of lightning incidence, including cosmic radiation, solar activity, and coupling between geomagnetic and interplanetary (solar wind) magnetic fields.
Abstract: A theoretical model is presented and described that unifies the complex influence of several factors on spatial and temporal variation of lightning incidence. These factors include the cosmic radiation, solar activity, and coupling between geomagnetic and interplanetary (solar wind) magnetic fields. Atmospheric electrical conductivity in the 10 km region was shown to be the crucial parameter altered by these factors. The theory reconciles several large scale studies of lightning incidence previously misinterpreted or considered contradictory. The model predicts additional strong effects on variations in lightning incidence, but only small effects on the morphology and rate of thunderstorm development.
01 Nov 1984
TL;DR: In this paper, mesoscale numerical forecasts utilizing the Mesoscale Atmospheric Simulation System (MASS) are documented for two East Coast severe weather events. The two events are the thunderstorm and heavy snow bursts in the Washington, D.C. - Baltimore, MD region on 8 March 1984 and the devastating tornado outbreak across North and South Carolina on 28 March 1984.
Abstract: Mesoscale numerical forecasts utilizing the Mesoscale Atmospheric Simulation System (MASS) are documented for two East Coast severe weather events. The two events are the thunderstorm and heavy snow bursts in the Washington, D.C. - Baltimore, MD region on 8 March 1984 and the devastating tornado outbreak across North and South Carolina on 28 March 1984. The forecasts are presented to demonstrate the ability of the model to simulate dynamical interactions and diabatic processes and to note some of the problems encountered when using mesoscale models for day-to-day forecasting.
TL;DR: In this article, the authors describe the test of a prototype system for airborne, advance detection of low-altitude wind shear by means of infrared remote sensing, which was conducted during the Denver Joint Airport Weather Studies (JAWS) project in the summer of 1982 aboard the NASA Ames B57B jet aircraft during several landing approaches and departures.
Abstract: Strong wind shears at low altitudes present severe hazards to aircraft during landing approach and takeoff. With aircraft operating near stall speed, a significant change in the wind speed and/or direction can result in a rapid loss or gain in altitude. Our objective is to describe the test of a prototype system for airborne, advance detection of such wind shear by means of infrared remote sensing. The test was conducted during the Denver Joint Airport Weather Studies (JAWS) project in the summer of 1982 aboard the NASA Ames B57B jet aircraft during several landing approaches and departures. The intent is to present analyses of the major results of this test and suggest its application to the passive, airborne detection of hazardous low-altitude wind shear (LAWS) before an aircraft encounter. This is critical for aircraft operating in an out of airfields without LAWS ground warning systems. This airborne wind shear detection and avoidance system is intended to augment the advanced, ground-based microwave, lidar, and low-altitude wind shear alert equipment as a secondary, airborne system. Even at distances as great as 12.5 miles (20 km) from thunderstorms, the wind shear in storm density currents can pose a real hazard to approaching and departing aircraft. It is concluded that the prototype airborne radiometer, observing in the 13 to 16 ^m portion of the atmospheric molecular spectrum of CO2, can sense the cold current outflow or gust front directly associated with low-altitude wind shear (LAWS) in the vicinity of thunderstorms at ranges up to 4 miles.
01 Jan 1984
TL;DR: In this article, a multispectral image-processing system for extracting mesoscale wind fields automatically from sequences of GOES imagery is described, which can produce equivalent or superior cloud-wind estimates compared to the time-consuming manual methods used on various interactive meteorological processing systems.
Abstract: A new multispectral image-processing system for extracting mesoscale wind fields automatically from sequences of GOES imagery is described. This system can produce equivalent or superior cloud-wind estimates compared to the time-consuming manual methods used on various interactive meteorological processing systems. Analysis of automated mesoscale cloud winds yield an estimated random error value of less than 1 m/s and produces both regional and mesoscale vector wind-field structure and divergence patterns that are consistent in time and highly correlated with subsequent severe thunderstorm development. As an example, the system is here applied to SMS II five-minute imagery from April 24, 1975 and the results are compared with manually obtained ones.
08 Jun 1984
TL;DR: In this article, extensive measurements of electric field components, radar cross-sections, thermal, and draft structure were made in and around large thunderstorms in central Florida during a previous flight program.
Abstract: : Extensive measurements of electric field components, radar cross- sections, thermal, and draft structure were made in and around large thunderstorms in central Florida during a previous flight program. Recent advances in analysis of the in-flight electric field data have been used to locate regions of localized charge concentrations in the large storm systems, thus providing guidance for possible real-time avoidance of zones of aircraft lightning strike hazard.